Polarization enhancement in two- and three-component ferroelectric superlattices

TL;DR

This study uses first-principles calculations to explore how layering different ferroelectric materials affects their polarization, revealing that specific layer compositions and thicknesses can significantly enhance polarization for nano-electro-mechanical applications.

Contribution

It demonstrates polarization enhancement in CaTiO_3/SrTiO_3/BaTiO_3 superlattices and identifies how layer thickness influences polarization and symmetry breaking, offering design insights for ferroelectric devices.

Findings

Polarization exceeds bulk BaTiO_3 when BaTiO_3 concentration is above 30%.

Layer thickness controls polarization enhancement.

Inversion-symmetry breaking can be tuned by layer thicknesses.

Abstract

Composition-dependent structural and polar properties of epitaxial short-period CaTiO_3/SrTiO_3/BaTiO_3 superlattices grown on a SrTiO_3 substrate are investigated with first-principles density-functional theory computational techniques. Polarization enhancement with respect to bulk tetragonal BaTiO_3 is found for two- and three-component superlattices with a BaTiO_3 concentration of more than 30%. Individual BaTiO_3 layer thickness is identified as an important factor governing the polarization improvement. In addition, the degree of inversion-symmetry breaking in three-component superlattices can be controlled by varying the thicknesses of the component layers. The flexibility allowed within this large family of structures makes them highly suitable for various applications in modern nano-electro-mechanical devices.